Vagus nerve contributes to the development of steatohepatitis and obesity in phosphatidylethanolamine N-methyltransferase deficient mice.

BACKGROUND & AIMS: Phosphatidylethanolamine N-methyltransferase (PEMT), a liver enriched enzyme, is responsible for approximately one third of hepatic phosphatidylcholine biosynthesis. When fed a high-fat diet (HFD), Pemt(-/-) mice are protected from HF-induced obesity; however, they develop steatohepatitis. The vagus nerve relays signals between liver and brain that regulate peripheral adiposity and pancreas function. Here we explore a possible role of the hepatic branch of the vagus nerve in the development of diet induced obesity and steatohepatitis in Pemt(-/-) mice. METHODS: 8-week old Pemt(-/-) and Pemt(+/+) mice were subjected to hepatic vagotomy (HV) or capsaicin treatment, which selectively disrupts afferent nerves, and were compared to sham-operated or vehicle-treatment, respectively. After surgery, mice were fed a HFD for 10 weeks. RESULTS: HV abolished the protection against the HFD-induced obesity and glucose intolerance in Pemt(-/-) mice. HV normalized phospholipid content and prevented steatohepatitis in Pemt(-/-) mice. Moreover, HV increased the hepatic anti-inflammatory cytokine interleukin-10, reduced chemokine monocyte chemotactic protein-1 and the ER stress marker C/EBP homologous protein. Furthermore, HV normalized the expression of mitochondrial electron transport chain proteins and of proteins involved in fatty acid synthesis, acetyl-CoA carboxylase and fatty acid synthase in Pemt(-/-) mice. However, disruption of the hepatic afferent vagus nerve by capsaicin failed to reverse either the protection against the HFD-induced obesity or the development of HF-induced steatohepatitis in Pemt(-/-) mice. CONCLUSIONS: Neuronal signals via the hepatic vagus nerve contribute to the development of steatohepatitis and protection against obesity in HFD fed Pemt(-/-) mice.

Hepatic ratio of phosphatidylcholine to phosphatidylethanolamine predicts survival after partial hepatectomy in mice.

UNLABELLED: A major predictor of failed liver resection and transplantation is nonalcoholic fatty liver disease (NAFLD). NAFLD is linked to a wide spectrum of diseases including obesity and diabetes that are increasingly prevalent in Western populations. Thus, it is important to develop therapies aimed at improving posthepatectomy outcomes in patients with NAFLD, as well as to improve the evaluation of patients slated for hepatic surgery. Decreased hepatic phosphatidylcholine (PC) content and decreased ratio of hepatic PC to phosphatidylethanolamine (PE) have previously been linked to NAFLD. To determine if decreased hepatic PC/PE could predict survival after hepatectomy, we used mouse models lacking key enzymes in PC biosynthesis, namely, phosphatidylethanolamine N-methyltransferase and hepatic-specific CTP:phosphocholine cytidylyltransferase α. These mice were fed a high-fat diet to induce NAFLD. We then performed a 70% partial hepatectomy and monitored postoperative survival. We identified hepatic PC/PE to be inversely correlated with the development of steatosis and inflammation in the progression of NAFLD. Decreased hepatic PC/PE before surgery was also strongly associated with decreased rates of survival after partial hepatectomy. Choline supplementation to the diet increased hepatic PC/PE in Pemt(-/-) mice with NAFLD, decreased inflammation, and increased the survival rate after partial hepatectomy. CONCLUSION: Decreased hepatic PC/PE is a predictor of NAFLD and survival following partial hepatectomy. Choline supplementation may serve as a potential therapy to prevent the progression of NAFLD and to improve postoperative outcome after liver surgery.

Phosphatidylcholine protects against steatosis in mice but not non-alcoholic steatohepatitis.

Several studies suggest that low levels of hepatic phosphatidylcholine (PC) play a role in the pathogenesis of non-alcoholic steatohepatitis (NASH). CTP: phosphocholine cytidylyltransferase (CT) is the key regulatory enzyme in the CDP-choline pathway for PC biosynthesis. Liver-specific elimination of CTα (LCTα(-/-)) in mice fed a chow diet decreases very-low-density lipoprotein secretion, reduces lipid efflux from liver, and causes mild steatosis. We fed LCTα(-/-) mice a high fat diet to determine if impaired PC biosynthesis played a role in development of NASH. LCTα(-/-) mice developed NASH within one week of high fat feeding. Hepatic CTα deficiency caused hepatic steatosis, a 2-fold increase in ceramide mass, and a 20% reduction in PC content. In an attempt to prevent NASH, LCTα(-/-) mice were either injected daily with CDP-choline or fed the high fat diet supplemented with betaine. In addition, LCTα(-/-) mice were injected with adenoviruses expressing CTα. CDP-choline injections and adenoviral expression of CTα increased hepatic PC, while dietary betaine supplementation normalized hepatic triacylglycerol but did not alter hepatic PC mass in LCTα(-/-) mice. Interestingly, none of the treatments normalized hepatic ceramide mass or fully prevented the development of NASH in LCTα(-/-) mice. These results show that normalizing the amount of hepatic PC is not sufficient to prevent NASH in LCTα(-/-) mice.

The role of histopathology in diagnosing protracted diarrhea of infancy.

Protracted diarrhea is used to describe infants with loose and frequent stools of sufficient severity to require nutritional support, most commonly parenteral nutrition. Despite similar clinical presentations, the causes of protracted diarrhea in infants are varied and diverse in management and prognosis. The following cases represent the two more common causes of protracted diarrhea in young infants in the developed world - allergic and autoimmune enteropathy. Both patients demonstrate diagnostic challenges related to clinical and/or laboratory features. These cases illustrate the important role histological assessment plays in determining the correct diagnosis, treatment course and prognosis in infants with protracted diarrhea.

Optimal length and usefulness of temporal artery biopsies in the diagnosis of giant cell arteritis: a 10-year retrospective review of medical records.

BACKGROUND: In giant cell arteritis, temporal artery biopsies often show vasculitis with giant cell formation, but optimal biopsy length for diagnosis is debated. We reviewed temporal artery biopsies from a 10-year period in the province of Alberta, Canada, to identify an ideal biopsy length in the diagnostic process for giant cell arteritis. METHODS: We retrospectively reviewed electronic medical records of patients who had undergone a temporal artery biopsy procedure in Alberta between Jan 1, 2008, and Jan 1, 2018, as reported in the Data Integration and Management Repository of Alberta Health Services. We extracted data on baseline demographic characteristics (sex and age), inflammatory markers (erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP]), temporal artery biopsy characteristics (side of biopsy and postfixation length), and final pathological diagnoses. All positive biopsies were reviewed by a single pathologist to ensure uniformity of pathological interpretation, with subsequent discordant results removed from analysis. Predictors of positive pathological diagnosis of giant cell arteritis were modeled by logistic regression, and the Akaike information criterion was used to compare logistic regression models with varying biopsy length cutoffs (0·5, 1·0, 1·5, 2·0, and 2·5 cm) to determine a change point for diagnostic sensitivity in postfixation length. FINDINGS: We extracted data on 1203 temporal artery biopsies; after removal of 13 discordant biopsies, 1190 biopsies from 1163 patients were reviewed. The mean age of patients was 72·0 years (SD 10·3) and 799 (68·7%) patients were women. 222 (18·7%) temporal artery biopsies were positive for giant cell arteritis. In univariable analysis, increases in age (71·3 years [SD 10·6] in negative biopsies vs 75·3 years [8·3] in positive biopsies; odds ratio [OR] 1·04 [95% CI 1·02-1·06]; p<0·0001)), ESR (36 mm/h [IQR 18-62] in negative biopsies vs 57 [31-79] in positive biopsies; 1·01 [1·01-1·02]; p<0·0001), CRP (12·1 mg/L [IQR 3·3-35·1] in negative biopsies vs 41·8 [14·6-82·4] in positive biopsies; 1·01 [1·01-1·01]; p<0·0001), and biopsy length (1·2 cm [IQR 0·9-1·7] in negative biopsies vs 1·6 [1·1-2·0] in positive biopsies; 1·28 [1·09-1·51]; p=0·0025) were associated with a positive pathological diagnosis. In multivariable analysis adjusted for age, ESR, and CRP, age (adjusted OR 1·04 [95% CI 1·02-1·05]; p=0·0001), CRP (1·01 [1·00-1·01]; p=0·0006), and biopsy length (1·22 [1·00-1·49]; p=0·047) remained statistically significant predictors. The Akaike information criterion determined a change point of 1·5 cm for diagnostic sensitivity. INTERPRETATION: Accounting for postfixation shrinkage, our findings suggest a 1·5-2·0 cm prefixation length as the optimal biopsy length to diagnose patients with giant cell arteritis, with greater lengths unlikely to provide significant additional diagnostic yield to justify risks associated with surgery. FUNDING: None.

Improved renal recovery with postresuscitation N-acetylcysteine treatment in asphyxiated newborn pigs.

Renal injury is one of the severe and common complications that occurs early in neonates with asphyxia, and reactive oxygen species have been implicated to play an important role on its pathogenesis. Improved renal recovery has been shown previously with N-acetyl-l-cysteine (NAC) in various acute kidney injuries. Using a subacute swine model of neonatal hypoxia-reoxygenation (H/R), we examined whether NAC can sustain its beneficial effect on renal recovery for 48 h. Newborn piglets were randomly assigned into a sham-operated group (without H/R, n = 6) and two H/R experimental groups (n = 8 each) with 2 h normocapnic alveolar hypoxia and 1 h 100% oxygen of reoxygenation followed by 21% oxygen for 47 h. Five minutes after reoxygenation, piglets received either normal saline (H/R control) or NAC (150-mg/kg bolus and 20 mg/kg per hour i.v. for 24 h) in a blinded, randomized fashion. All piglets were acidotic and in cardiogenic shock after hypoxia. Treating the piglets with NAC significantly increased both renal blood flow and oxygen delivery throughout the reoxygenation period. N-acetyl-l-cysteine treatment also improved the renal function with the attenuation of elevated urinary N-acetyl-ß-d-glucosaminidase activity and plasma creatinine concentration observed in H/R controls (both P < 0.05). The tissue levels of lipid hydroperoxides and caspase 3 in the kidney of NAC-treated animals were significantly lower than those of H/R controls. Conclusively, postresuscitation administration of NAC elicits a prolonged beneficial effect in improving renal functional recovery and reducing oxidative stress in newborn piglets with H/R insults for 48 h.